1. Field of the invention
The present invention relates to an inspection method and an inspection system of a terminal metal fitting for judging the good or bad of the fastening condition of an electric wire by a crimping piece of the terminal metal fitting.
2. Description of the Related Art
A wiring harness is arranged on a motor vehicle in order to supply electric power from power source such as a battery to onboard equipment such as various kinds of lamps or motors. The above wiring harness has a plurality of electric wires, a pressure welding terminal as a terminal metal fitting attached to an end portion of each electric wire, and a connector housing accommodating the pressure welding terminal.
The above pressure welding terminal has a wire connecting portion which it is electrically connected to the above electric wire and fastens it. The above wire connecting portion has a wall carrying the above electric wire, a pressure welding portion pressure-welded to the above electric wire and a crimping piece. The pressure welding portion has a pair of press-fit blades to press the electric wire therebetween.
The electric wire is pressed into a pair of press-fit blades, the above press-fit blades cut into a sheathing portion of the electric wire and are put into contact with a core wire, and then the above pressure welding portion is electrically connected to the electric wire. Crimping pieces are stood on respective edges of the above wall. The crimping pieces each are bent toward the above wall, and the electric wire placed on the above wall is fastened by the crimping pieces.
The above-described pressure welding terminal is inserted in a terminal accommodating groove of the connector housing of insulative synthetic resin, and the electric wire is pressed between press-fit blades. When the electric wire is pressed into press-fit blades, a well-known pressure welding apparatus is used.
The above pressure welding apparatus has a pressure welding blade of metal and a pair of guides to guide the pressure welding blades. First, the wire connecting portion is sandwiched between the guides. Subsequently, the pressure welding blade presses the electric wire into press-fit blades and bends the crimping pieces toward the above wall.
With respect to the above prior art pressure welding apparatus, however, when the electric wire is pressed into press-fit blades, that is, when the electric wire is pressure-welded to the wire connecting portion, the above guide is likely to get out of position, and therefore the pressure welding blade is not often put into contact with the crimping piece.
And, when the connector housing has a plurality of pressure welding terminals in parallel, if the guide makes a position divergence, the above pressure welding blade would be put into contact with a crimping piece of the adjoining pressure welding terminal instead of the aiming pressure welding terminal. In this case, the crimping piece of the adjoining pressure welding terminal is reversely bent outwardly, thereby not fastening the electric wire.
And, a visual inspection has been conventionally carried out in order to judge the good or bad of the fastening condition of the electric wire by the crimping piece of the pressure welding terminal. In the visual inspection, a defective could be judged to be a non-defective by skill level of a worker, and a judgement of the good or bad would be different at every worker, thereby judging a defective to be a non-defective. This caused an assembly of a defective on the wiring harness.
In view of the foregoing, an object of the present invention to provide an inspection method and an inspection system of a terminal metal fitting which can securely judge the good or bad of the fastening condition of an electric wire by a crimping piece of the terminal metal fitting.
In order to achieve the above object, as a first aspect of the present invention, an inspection method of a terminal metal fitting having an wire connecting portion having a wall carrying an electric wire and a crimping piece bent toward the wall so as to fasten the electric wire between the crimping piece and the wall comprises the steps of: illuminating the wire connecting portion fastened to the electric wire; binary-processing an image of the wire connecting portion illuminated; calculating an area less than or not less than a threshold value in image information obtained by the binary processing; and judging good or bad of a fastening condition of the electric wire by the crimping piece on a basis of the area.
As a second aspect of the present invention, an inspection system of a terminal metal fitting having an wire connecting portion having a wall carrying an electric wire and a crimping piece bent toward the wall so as to fasten the electric wire between the crimping piece and the wall comprises: a light source to illuminate the wire connecting portion; an image-taking means to take an image of the wire connecting portion; a dark box, with a dark inner surface, to cover at least an object side of the image-taking means, the light source, and the terminal metal fitting for preventing outer light from shining on the wire connecting portion; and a judging means to binary-process an image of the wire connecting portion illuminated by the light source and judge good or bad of a fastening condition of the electric wire by the crimping piece on a basis of an area less than or not less than a threshold value in image information obtained by the binary processing, wherein the image-taking means and the light source are arranged so that the light thrown from the light source and reflected by the crimping piece does not enter the image-taking means, and a sheathing portion of the electric wire is a light color.
As a third aspect of the present invention, based on the second aspect, the image-taking means faces the wall of the wire connecting portion to which the electric wire is fastened, and the light source is arranged at a position of making an angle xcex8 between a line connecting the light source with the crimping piece and a direction of the electric wire fastened to the wire connecting portion so that the light thrown from the light source and reflected by the crimping piece does not enter the image-taking means.
As a fourth aspect of the present invention, based on the third aspect, the light source is arranged at a position of making the angle xcex8 of not more than 45 degrees.
As a fifth aspect of the present invention, an inspection system of a terminal metal fitting having an wire connecting portion having a wall carrying an electric wire and a crimping piece bent toward the wall so as to fasten the electric wire between the crimping piece and the wall comprises: a light source to illuminate the wire connecting portion; an image-taking means to take an image of the wire connecting portion; a judging means to binary-process an image of the wire connecting portion illuminated by the light source and judge good or bad of a fastening condition of the electric wire by the crimping piece on a basis of an area less than or not less than a threshold value in image information obtained by the binary processing, wherein the image-taking means and the light source are arranged so that the light thrown from the light source and reflected by the crimping piece enters the image-taking means.
As a sixth aspect of the present invention, based on the fifth aspect, the image-taking means faces the wall of the wire connecting portion to which the electric wire is fastened, and the light source faces the wall of the wire connecting portion, to which the electric wire is fastened, near the image-taking means so that the light thrown from the light source and reflected by the crimping piece enters the image-taking means.
As a seventh aspect of the present invention, based on any one of the second to sixth aspects, the judging means judges good or bad of a fastening condition of the electric wire on a basis of an area less than or not less than a threshold value in an inspection area in the image of the wire connecting portion taken by the image-taking means, the inspection area being provided for each crimping piece and including at least partial image of the crimping piece.
As an eighth aspect of the present invention, based on the seventh aspect, the inspection area is positioned over a longitudinal axis of the electric wire fastened to the wire connecting portion.
According to the above-described structures of the present invention, the following advantages are provided.
(1) Because the intensity of the reflected light of the terminal metal fitting and the electric wire is different when the wire connecting portion is illuminated, the crimping piece and the electric wire can be distinguished by binary-processing the image of the crimping piece. Because states of the crimping pieces, that is, standing perpendicularly to the wall, being bent outwardly of the wire connecting portion, and being bent inwardly toward the wall while fastening the electric wire, can be easily distinguished, the good or bad of the fastening condition of the electric wire by the crimping piece can be easily judged. Therefore, on the basis of an area not less than or less than the threshold value in the binary image, the good or bad of the fastening condition of the electric wire by the crimping piece can be securely judged.
(2) Viewing from the image-taking means, the dark inner surface of the dark box is reflected in the crimping piece and the sheathing portion of the electric wire is a light color. Therefore, when the image of the wire connecting portion obtained by the image-taking means is binary-processed, the electric wire securely becomes xe2x80x9cnot less than the threshold valuexe2x80x9d and the crimping piece securely becomes xe2x80x9cless than the threshold valuexe2x80x9d. Therefore, the electric wire and the crimping piece can be more securely distinguished. Therefore, on the basis of an area not less than or less than the threshold value in the binary image, the good or bad of the fastening condition of the electric wire by the crimping piece can be more securely judged.
(3) The light source is arranged at a position of making an angle between the line connecting the light source with the crimping piece and the direction of the electric wire fastened to the wire connecting portion. Therefore, because the light thrown from the light source and reflected by the crimping piece does not securely enter the image-taking means, when the image of the wire connecting portion obtained by the image-taking means is binary-processed, the electric wire and the crimping piece can be more securely distinguished. Therefore, on the basis of an area not less than or less than the threshold value in the binary image, the good or bad of the fastening condition of the electric wire by the crimping piece can be still more securely judged.
(4) The light source is arranged at a position of the angle of not more than 45 degrees. Therefore, because the light thrown from the light source and reflected by the crimping piece does not securely enter the image-taking means, when the image of the wire connecting portion obtained by the image-taking means is binary-processed, the electric wire and the crimping piece can be more securely distinguished. Therefore, on the basis of an area not less than or less than the threshold value in the binary image, the good or bad of the fastening condition of the electric wire by the crimping piece can be still more securely judged.
(5) The image-taking means and the light source are arranged so that the light thrown from the light source and reflected by the crimping piece enters the image-taking means. Therefore, when the image of the wire connecting portion obtained by the image-taking means is binary-processed, the electric wire securely becomes xe2x80x9cless than the threshold valuexe2x80x9d and the crimping piece securely becomes xe2x80x9cnot less than the threshold valuexe2x80x9d. Therefore, the electric wire and the crimping piece can be more securely distinguished. Therefore, on the basis of an area not less than or less than the threshold value in the binary image, the good or bad of the fastening condition of the electric wire by the crimping piece can be more securely judged.
(6) The image-taking means and the light source face the wall of the wire connecting portion, and the light source is arranged near the image-taking means. Therefore, because the light thrown from the light source and reflected by the crimping piece securely enters the image-taking means, when the image of the wire connecting portion obtained by the image-taking means is binary-processed, the electric wire and the crimping piece can be more securely distinguished. Therefore, on the basis of an area not less than or less than the threshold value in the binary image, the good or bad of the fastening condition of the electric wire by the crimping piece can be still more securely judged.
(7) The judging means judges the fastening condition of the electric wire by the crimping pieces on the basis of an area, corresponding to each crimping piece, of not less than or less than the threshold value in the inspection area. Therefore, the fastening condition of the electric wire can be more unerringly judged than a case of providing one large inspection area over a plurality of crimping pieces.
(8) Because the inspection area is positioned over the center of the electric wire, an area not less than the threshold value and an area less than the threshold value of the inspection area sensitively vary according to the good or bad of the crimping piece. Therefore, the electric wire and the crimping piece can be still more securely distinguished. And, on the basis of an area not less than or less than the threshold value in the binary image, the good or bad of the fastening condition of the electric wire by the crimping piece can be still more unerringly and securely judged.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.